Nissan manufactured the N1 block a little unique than the standard RB26 block, and is marked with a 24U rather than 05U to differentiate it.The RB-X GT2 (built and built by REINIK) is an engine specifically designed for that NISMO 400R. The difference between this engine along with a RB26DETT would be that the engine is bored and stroked 87 mm �